This section provides background information related to the present disclosure which is not necessarily prior art. The connecting parts that are known for radiators of motor vehicles are formed by a plastic tank part. The plastic tank part has a width and length corresponding to the width and height of the radiator. Provided at the bottom of the tank part is a connection sleeve to supply and take away the operating fluid emerging into the internal space of the tank part.
The drawback of these known connecting parts is that a pressure drop of the operating fluid occurs in them, which substantially influences the overall performance of the heat exchanger. The pressure drop in the operating fluid occurs especially in the region of sharp edges where the inner wall of the connection sleeve passes into the wall of the tank part (and vice versa) and which are created during the manufacture of the plastic connecting part by injection molding.